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Earth Science > Air Pressure and Wind > Flashcards

Air Pressure and Wind Flashcards

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1
Q

What is air pressure do?

A
  • Controls all air movement in the atmosphere
  • Air (wind) moves from areas of high to low pressure
  • Hourly variations in air pressure give strong indications of weather in the next few hours
  • Works in all directions
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2
Q

What is the weight of the atmosphere over a square inch of the Earth’s surface at sea level?

A

14.7 lbs per square inch

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3
Q

How does a mercury barometer work?

A
  • 1643: barometer invented by Evangelista Torricelli:
  • Mercury vapor is more dangerous
  • Placed a glass cylinder inside the vat of mercury
  • Lifts it up and places it in upright
  • Mercury fell down cylinder and stopped close to top
  • Water will do the same thing, but the barometer would have to 13.5 times bigger to account for the 14.7 pounds of water
  • The higher the mercury goes up, the higher the pressure is
  • The lower the mercury level is, the lower the pressure is
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4
Q

How does air pressure change with height?

A

Decreases

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5
Q

How does air pressure change as temperature changes?

A

Colder air indicates high pressure because it is denser than warm air, which indicates low pressure

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6
Q

How does air pressure change as specific humidity changes?

A
  • Air pressure decreases with increasing specific humidity

- Increases with decreasing specific humidity because water is a light molecule

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7
Q

What kind of weather is associated with high and low pressure?

A

High pressure: sunny weather

Low pressure: rainy weather and clouds

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8
Q

What makes the wind blow?

A

If isobars are closer together, wind wants to go go from areas of high pressure to low areas of low pressure

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9
Q

What is pressure gradient force and how is it responsible for wind currents?

A

This force moves air from high to low pressure, creating wind currents

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10
Q

What two things control the direction of the wind?

A

Pressure gradient force and the Coriolis effect

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11
Q

What causes the Coriolis effect?

A
  • Related to the rotation of the Earth
  • Air is deflected to the right as it moves across the surface of the Earth in the northern hemisphere
  • Deflected to the left in the southern hemisphere
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12
Q

How does the Coriolis effect affect the direction of wind movement? (for N and S)

A

NORTHERN HEMISPHERE:
1) Wind movement: right
2) High pressure system: right (clockwise)
3) Low pressure system: left (counterclockwise)
SOUTHERN HEMISPHERE:
1) Wind movement: left
2) High pressure system: left (counterclockwise)
3) Low pressure system: right (clockwise)

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13
Q

How does the Coriolis effect affect the movement of warm and cold water currents in the ocean?

A

Northern Hemisphere: currents move right (clockwise)

Southern Hemisphere: currents move left (counter-clockwise).

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14
Q

In what direction would the winds blow if the Earth were not rotating?

A
  • Winds would blow toward the equator
  • They would blow south in the Northern Hemisphere
  • North in the Southern Hemisphere
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15
Q

In air pressure belts:
when is air rising or falling?
when is air pressure high or low?

A
  • Air rises at lows, and falls at highs

- Air pressure is high when an area is below sinking air, and low when an area is below rising air

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16
Q

Why is the Intertropical Convergence Zone an area of high rainfall?

A
  • The air there is warm, and warm air has a lower density, so it rises
  • Rising air creates clouds, and causes rain
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17
Q

Why are areas of the Earth’s surface at around 30 degrees N and 30 degrees S zones of relatively high air pressure and low rainfall?

A
  • Smaller circle around 30 than at the equator
  • Air from equator bent right/left, doesn’t reach poles, stops at 30 degrees
  • Cold air sinks over these areas, which is denser than warm air, sinking air inhibits clouds
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18
Q

What are the changes in meteorological data that occur as a front passes through an area? (Cold front)

A

Cold front passing through:
Warm&raquo_space;> cold
Moist&raquo_space;> dry
Low air pressure&raquo_space;> high air pressure

19
Q

Where are the wind belts: trade winds, westerlies, and polar easterlies?

A 
90-60 N: Polar North-Easterlies
60-30 N: Prevailing South-Westerlies
30-0 N: Northeasterly Trade Winds
0-30 S: Southeasterly Trade Winds
30-60 S: Prevailing North-Westerlies
60-90 S: Polar South-Easterlies
20
Q

Where are the different air pressure belts on a map of the world (Intertropical Convergence Zone, polar highs, subtropical highs, and subpolar lows)?

A

0: Intertropical Convergence Zone
30: Sub-Tropical High
60: Sub-Polar Low
90: Polar Hugh

21
Q

Coriolis Effect

A
  • As the Earth rotates, air is deflected to the right as it moves across the surface of the Earth in the northern hemisphere
  • Deflected to the left in the southern hemisphere
22
Q

Doldrums

A

Refers to the ITCZ where ships can get stuck in windless waters

23
Q

Easterlies

A

Winds in the polar regions that blow from the east

24
Q

Gyre

A
  • A circular pattern of ocean currents
  • Clockwise in the Northern Hemisphere
  • Counterclockwise in the Southern Hemisphere
  • Warm water current- gulf stream
  • Circular because of the wind belts
  • Garbage collects in center of gyre
25
Q

Horse Latitudes

A

30 degrees north and south of the equator, where there can be windless waters

26
Q

Intertropical Convergence Zone (ITCZ)

A

On the equator, where warm air rises, creating an area of low pressure

27
Q

Isobar

A
  • Iso means same
  • Lines on a weather map that connect areas of equal air pressure
  • Exists every 4 millibars, in multiples of four, to show air pressure
28
Q

Millibar

A

Used to measure barometric pressure on a map

29
Q

Pressure Gradient Force

A

Air moves from areas of high to low pressure, creating wind currents

30
Q

Trade Winds

A
  • Steady winds blowing northeast in the Northern Hemisphere
  • Southeast in the Southern Hemisphere
  • Located above and below the ITCZ
31
Q

Westerlies

A

Wind between the trade winds and polar easterlies that blow to the west

32
Q

Wind

A

Movement of the air, especially in the form of a current of air blowing from a particular direction

33
Q

Why is the atmosphere so spread out?

A

All the molecules move around and the force of collisions push the molecules out

34
Q

Oxygen

A
  • In a cubic cm of air: 24 sextillion molecules of air
  • O2 molecule = 425 meters / second
  • On average each molecules experiences 6.6 billion collisions per second
  • In intergalactic space: there is 1 atom per cubic meter and experiences 1 collision every 2.9 billion years
35
Q

Air pressure

A
  • The weight of the atmosphere over a specified area of the Earth’s surface
  • Gravitational component and the force of colliding air molecules component
36
Q

1) Global Wind that moves weather across US

2) Warmest Global Wind air

A

1) Prevailing South-Westerlies

2) Trade Winds

37
Q

What causes changes in air pressure?

A

1) Entry into your area of an air mass with higher or lower air pressure
2) Temperature (colder = denser = higher air pressure)
3) Changes in specific humidity (adding a light element (water), amount of heavy molecules going down, humid day = low air pressure)

38
Q

Average sea level air pressure in:

1) pounds / square inch
2) millibars
3) g /cm
4) kg / square cm
5) torr

A

1) 14.7 pounds / square in
2) 1013.25 millibars
3) 1013.25 g / cm
4) 1.01325 kg / square cm
5) 760 torr

39
Q

Average air pressure of mercury (inches, torr, millibars)

A

29.92 inches
760 mm = 760 torr
1013.25 millibars

40
Q

What are the factors that determine how fast winds move by pressure gradient force?

A

1) How far apart the areas of high and low pressure are (closer = faster)
2) The difference in pressure between the high and low pressure areas (greater difference = faster)

41
Q

Why does Europe have milder winters?

A

-Paris much high latitude than us but they have milder winters
-Gulf stream brings warm water to Europe
Westerly wind belt blows the warm air away from us

42
Q

What is the boundary between polar easterlies / westerlies like?

A
  • Wavy, climate very changeable

- Jet stream flows along this boundary, propelling low pressure systems

43
Q

Moon phase

A

Waxing crescent

Earth Science (16 decks)

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